Ethylated-di-isopropyl benzene



- Patented M01 7, 1939 UNITED STATE ETHYLATED-DI-ISOPROPYL BENZENE Robert R. Dreisbach, Midland, Micln. assignor to The Dow Chemical Company, Midland, Mich., a corporation of Michigan No Drawing. Application my 18, 1936,

Serial No. 91,428

5 Claims.

This invention concerns certain new organic products consisting essentially of benzene derivatives having the formula products are useful as organic solvents and as dielectric agents. Certain of them are adapted to 26 special uses, e. g. as agents for incorporation in motor fuels such as gasoline containing lead tetra-ethyl, to increase the octane rating thereof. A mixture of isomeric diethyl-di-isopropyl-benzenes is disclosed in my copending application, Serial No. 16,216, filed April 13', 1935, of which the present application is a continuation in part.

My new products may be prepared in several ways, e. g. by reacting benzene, or a halobenzene containing not more than 3 halogen atoms, suc- 30 cessively with ethylene and propylene in the presence of a Friedel-Craft catalyst, or by similar procedure using an ethyl halide, e. g. ethyl bromide or chloride, and an isopropyl halide. as the alkylating agents. The ethylated di-iso- 'propyl-halobenzenes may also be prepared by reacting benzene successively with ethylene and propylene, or the corresponding alkyl halides, to form an ethylated di-isopropyl-benzene containing not more than 5 alkyl groups and thereafter 40 reacting the latter with a halogen, e. g, chlorine or bromine, under conditions such that the halogen enters the benzene ring rather than the alkyl radicals.

In practice I prefer to operate as follows:--

Benzene and between 0.05 and 0.1 molecular equivalent of aluminum chloride, or other Friedel- Craft catalyst, are placed in a closed reactor provided with an agitator. Ethylene is then passed into the reactor at approximately room temperature while stirring the reaction mixture and maintaining the same under a moderate pressure, e. g. up to 100 pounds per square inch. Operation in such manner is continued until suflicient ethylene has been introduced to ethylate the benzene to a stage containing between 1' and 4 ethyl groups per molecule. The introduction of ethylene is then discontinued and propylene is added to the mixture under the conditions stated above until approximately 2 moles of propylene have been added per mole of the benzene initially employed. The introduction of propylene is then stopped and the mixture is allowed to stand for some time, e. g. 0.5 hour or longer. During this period a heavy sludge layer containing the cata-. lyst-usually settles to the bottom of the reactor. 10 This heavy layer is drawn off for re-employment as a catalyst in successive reactions and the clear supernatant layer containing the ethylated diisopropyl-benzene is washed with water and neutralized with an aqueous alkali. It is then dried 15 and fractionally distilled to separate the ethylated di-isopropyl-benzene product. The product so obtained is a liquid usually consisting of a mixture of isomeric ethylated di-isopropyl-benzene compounds. It contains two isopropyl radicals and from one to four ethyl groups per molecule.

If desired, instead of first ethylating benzene to the monoethyl-tetraethyl benzene state, as described above, and thereafter reacting the mixture with propylene, an individual monoethyl-, diethyl-, methyl-, or tetraethyl-benzene from any source may be reacted with propylene in the presence of a Friedel-Craft catalyst to form the ethylated di-isopropyl-benzene product. The latter is more easily purified when prepared in 30 such manner than when prepared using crude ethylated benzene, i. e. the undistilled mixture obtained by the ethylation of benzene, as a starting material.

When the ethylated di-isopropyl benzene prodnot contains not more than 3 ethyl groups per molecule, it may be reacted with chlorine or bromine at moderate temperatures, e. g. temperatures not exceeding 50 C., in the presence of iron and in the dark to obtain a corresponding .mix- 40 ture of nuclear halogenated ethylated di-isopropyl-benzene compounds. This product also is a liquid at room temperatures. It is particularly useful as a dielectric agent. I

The following examples illustrate a number of 45 ways in which the principle of the invention has been employed but are not to be construed as limiting the invention:-

Example 1 A mixture of 20 pounds, 10 ounces of ethyl benzene and 1.5 pounds of aluminum chloride was placed in a closed reactor provided with a' mechanical stirrer. Propylene was then introduced to the mixture while agitating and main- 55 2 taining the latter at temperatures between 20 and 30 C. until 10 pounds, 10 ounces of propylene had been added. Aiter all oi the propylene had been added the mixture was permitted to settle, the sludge layer thereof was separated and the remaining material was washed successively with water and aqueous alkali, dried, and iractionally distilled, the traction distilling between 210- C. and 223 C. being collected. This fraction was redistilled, whereby a mixture of isomeric monoethyl-di-isopropyl-benzenes was separated. The

mixture boiled at approximately 227 C. under 744 i millimeters pressure and had an index of retraction of 1.4898 at 25 C. and a specific gravity of 0.857 at 25 C. with respect to water at the same temperature. On analysis it was found to contain 11.6 per cent of hydrogen and 88.4 per cent 01' carbon, which corresponded very closely to.

theoretical.

' Example 2 poises; index of refraction-1.4968 at 25 C. specific gravity at 60 F. (15.6" C.)-0.875, at 100 F. (37.8 C.) 0.863. The product. contained 11.8 per cent by weight of hydrogen and 88.2 per cent of carbon, which corresponded closely to theoretical.

' Example 3 Triethyl-benzene, which had been formed by reacting ethylene with benzene and distilling the product, was treatedwith propylene in the presence of aluminum chloride to form a mixture comprising triethyl-di-isopropyl benzene. The product was then separated as in Example 1. Two fractions of said product were obtained, viz.,

a fraction boiling at about 284 C. under 744 millimeters pressure and having a specific gravity of 0.886 at 25 C. with respectto water at the same temperature and another fraction boiling at about 278 C. under 748 millimeters pressure and hav- .ing aspecific'gravity of 0.882 at 25 C. Both of said products were permanent liquids analyzing correctly as triethyl-di-isopropyl-benzene, being mixtures of isomeric compounds.

Example 4 A mixture of 305 grams of the .diethyl-di-isopropyl-benzene product described in Example 2, 100 grams oi glacial acetic acid, 50 grams of sodium acetate, and. 15 grams of iron filings was stirred and maintained at approximately 40 C.

. while 198.5 grams of chlorine gas was gradually passed thereinto. The mixture was then washed with water, dried and fractionally distflled.

There was separated a fraction boiling at approximately 284 C. under 741 millimeters pressure and having an index of refraction of 1.5196 at 25 C. and a specific gravity of 0.985,at 25 C.

' with respect to water at the same temperature.

This fraction was found on analysis to be diethyldi-i'sopropyl-mono-chlorobenzene. It was a liquid at room temperature.

compounds be employed.

Example 5 A mixture'oi 227 grams of diethyl-di-isopropylbenzene, 150 grams of glacial acetic acid. 50 grams of sodium acetate and grams of iron filings was stirred and maintained at temperatures between 40 and 45 C; while 92 grams of bromine was gradually added thereto. The mixture was then washed and iractionally distilled whereby a fraction was separated which boiled at about 296 C. under 742 millimeters pressure, had an index of refraction of 1.5324 at 25 C. and a spa;

cific gravity oi 1.143 at 25 C. with respect to water at the same temperature, and analyzed correctly as diethyl-dieisopropyl-bromo-benzene. It was a liquid at room temperature.

Example 6 A mixture of 393 grams of diethyl-di-isopropyibenzene, 200 grams of glacial acetic acid, 50 grams of sodium acetate and '10 grams or ironfllings was treated with 217 grams of bromine at tem-' peratures between 40 and 50 C., the bromine being added tothe mixture gradually and with stirring. After all of the bromine had been added,

the mixture was washed, dried and iractionally distilled whereby a fraction was separated which boiled at 321 C. under 745 millimeters pressure, had an index of retraction of 1.5597 at C. and a specific gravity of 1.386 at 25 C. with respect to water at the same temperature and analyzed correctly as diethyl-di-isopropyl-dibromo-benzene. The product was a liquid at room temperature.

Other modes of applying the principle of my invention may be employed instead of those explained, change being made as regards the method or compounds herein disclosed, provided the steps or compounds stated by the following' claims or the equivalent of such stated steps or I therefore particularly point out tinctly claim as my inventlon:--

1. A compound having the general formula and disj wherein n is an integer not exceeding 4.

2, A liquid mixture of compounds having the eneral formula wherein n is an integer not exceeding 3. A mixture of isomeric monoethyl-di-isopropyl-benzenes having a boiling point of appromiately 227 C. at 744 millimeters pressure and the specific gravity of about 0.857 at 25 C.'

with respect to water at the same temperature.

4. A mixture of isomeric diethyl-di-isopropylbenzenes having a boiling 'point in the range between 250 and 255 C. at 750 millimeters pressure.

5. A mixture of isomeric tr'iethyl-di-isopropylbenzenes having a boiling point of approximately 277.6 C. at 748 millimeters pressure and having a specific gravity of about 0.882 at 25 C. with respect to water at the same temperature.

' ROBERT a. DREISBACH. 

